This information was taken from White-tailed Deer: Ecology and Management. It is A Wildlife Management Institute Book, Compiled and Edited by Lowell K. Halls, published by Stackpole Books, copyright 1984 by the Wildlife Management Institute.

Modern members of the deer family are slim, often long-legged and graceful. They have the ability to run, leap and skulk to evade enemies. They possess deciduous antlers, except in the aberrant musk deer and Chinese water-deer (Hydropotes). Only males have antlers, except in Rangifer, where females are also endowed. Hormones from the testes, the anterior lobe of the pituitary gland, and the thyroid affect antler development. The upper canines are long and tusklike only in three genera (in the Subfamilies Moschinae and Cervulinae), being reduced greatly or absent in all others. The molars are low-crowned (brachyodont) with "half-moon"-shaped cusps (selenodont). The dental formula of deer is: incisors, 0/3; canines, 0/1 or 1/1; premolars, 3/3; molars, 3/3; a total of 32 or 34 teeth. In the skull, the lacrimal and nasal bones are not contiguous. The cannon bone in each limb is fomed by the fusion of the two principle metapodials of the third and fourth toes. Lateral toes (remnants of the second and fifth toes) are reduced. The four-chambered ruminating stomach is a prominent feature of the soft anatomy (interal organs) and important in the digestive process. The primitive musk deer is the only cervid with a gall bladder. Tarsal, metatarsal or interdigital glands may be present. Facial glands occur in all genera except the musk deer. Males usually are larger than females. Both sexes may have specific courtship behaviors, and males often maintain harems. The gestation period is five to eight months. Young frequently have spotted coats, but adults rarely do. Living Cervidae include four subfamiles, 17 genera and approximately 37 species (Ellerman and Morrison-Scott 1951, Cabrera 1961, Coopman 1967).

The continental distribution of modern cervid genera indicates a high degree of species endemism in Asia (mostly southeastern) and in South America. Genera in the subfamilies Moschinae, Cervulinae and Cervinae are Eurasian in derivation, with only Cervus in the Cervinae spreading into the New World in the Pleistocene, presumably by way of the Bering Strait land-bridge that once connected the Soviet Union's Chukchi Peninsula with the Seward Peninsula in Alaska. Genera in the subfamily Odocoileinae, with the exception of Hydropotes and Capreolus, are typical of the Western Hemisphere. In South America, secondary diversity, probably from Odocoileus as stem stock (Hershkovitz 1982, Simpson 1945), resulted in the development of at least 10 cervid genera (5 Recent). Alces and Rangifer, two northern genera, presumably made their way to Eurasia by traveling across the Bering land-bridge, perhaps meeting east-traveling Cervus enroute. Modern mammalogists regard as minor the differences between the pairings: American elk (or "wapiti") and Eurasian red deer; North American moose and Eurasian elk; and caribou and reindeer. Despite their present separation by the Bering Strait, these relatives are considered to belong to the same species--Cervus elaphus, Alces alces, and Rangifer tarandus respectively.

THE GENUS ODOCOILEUS

As mentioned previously, the ancestral American Odocoileus seems to have been the progenitor of the several endemic South American deer. In fact a few authors (see Grzimek 1972) have suggested that some of the Neotropical deer--marsh deer (Ozotocerus), Pampas deer (Blastocerus) and huemal (Hippocamelus)--be placed within the genus Odocoileus. However, most modern authorities include only white-tailed deer (O. virginianus) and mule and black-tailed deer (O. hemionus. Distinctive generic characteristics most commonly used to separate Odocoileus from other New World cervids include: from Rangifer--the absence of antlers in females, the presence of nonpalmate antlers, and a hairless muzzle; from Cervus--the absence of upper canine teeth (except in rare instances), and also of the upper ends of the lateral metacarpals and the vomer dividing the posterior narial cavity; from Alces--the presence of nonpalmate antlers, the absence of a dewlap and also of the vomer dividing the posterior narial cavity; from Pudu--the presence of large antlers and metatarsal, tarsal and pedal glands, and also the naviculo-cuboid of the tarsus being free from the cuneiform; from Ozotoceros, Blastocerus, Hippocamelus and Mazama--the presence of metatarsal glands. The white-tailed deer is distinguished from the mule deer by the shape and configuration of the antlers, the length of the sub-basal snag on the antlers, the lengths of the ears and metatarsal glands, the color of the dorsal tail hairs, and the condition of the lacrimal fossa. Distinguishing between the two species is a problem only where their ranges overlap.